1. Field of the Invention
The invention relates to attaching or soldering BGA packaged components to substrates, and, in particular, to circuit boards in the process of reworking the circuit boards.
2. Background
Ball grid array (BGA) packages present many advantages to the electronics industry, such as reduced package size, increased input/output switching, and resiliency for initial production placement, because of the absence of leads typical to most surface mount components, which are susceptible to bending/deforming while handling.
One of the principal drawbacks to BGA packages has been the difficulty of replacing a BGA package back on a printed circuit board (PCB) during rework or repair. The process of rework and repair of a PCB is typically done in a selective manner, that is, not in a high volume or repetitive manner. In rework, each component package is usually individually removed and replaced, without use of the expensive pick and place machinery, with optical alignment features, that are generally used in the initial manufacture. Thus, because a BGA package does not allow a rework technician visibility under the BGA package to align the package's solder balls with the corresponding solder pads on the PCB, a serious problem has long existed for the rework technician who does not have use of such expensive pick and place machinery.
A currently available solution to this problem is a split beam vision system consisting of a prism, video camera, and monitor. Briefly, the camera with the aid of the prism allows the technician to "see" both the balls underneath the BGA and the grid of pads on top of the PCB where it is to be placed. By superimposing the two images on top of each other, an accurate alignment can be made before placing the BGA on the PCB to the soldered. This is a very costly solution.